The proportions of neutrophil states were compared at t1, and this revealed a divergent expansion of IFNactive neutrophils (clusters 2, 4 and 5) marked by IFITM1 expression in COVID-19, which became similar to bacterial ARDS at t2 (Fig. 1f–h and Extended Data Fig. 4m–o). The gene discussed is IFITM1; the disease is COVID-19.